1. Field of the Invention
This invention relates to a mechanism used to hold a gumbox on an envelope machine steady as it is being raised and lowered to a position for contact with gum applying rollers for transferring gum or latex sealing material from the gumbox to an envelope and more particularly, a mechanism comprising a friction brake and safety slip clutch disposed between a manual hand crank pinion used to raise and lower the gumbox and the gumbox.
2. Description of the Prior Art
Apparatus for applying sealing material to envelopes generally consists of a conveyor which takes a folded envelope from a hopper or an unfolded blank from the hopper which is then folded, and successively feeds the folded envelope past a latex sealing material applicator which applies the latex sealing material to spaced portions of the envelope which would normally be sealed after insertion of the contents, and then drying apparatus where the wet latex is dried but can be remoistened for sealing purposes. The envelopes are then removed from the conveyor and stacked. An example of such an apparatus is shown in U.S. Pat. No. 3,965,851, assigned to the same assignee as the instant invention.
The latex applicator is placed in contact with one or more gumboxes. The gumboxes are raised or lowered into contact with the applicator, which usually includes at least one latex transfer roller. The latex transfer roller rotates through the gumbox and transfers latex sealing material to an applicator contact roll whose nip is tangent to and opposite an impression roll. The applicator contact roll can be provided with a suitable latex applying pattern and the folded envelopes are held on the conveyor and sent between the nip of the impression and applicator contact roll wherein latex is transferred from the applicator contact roll to the envelope in the predisposed pattern, and then the envelope is conveyed to a suitable oven to dry the latex sealing material.
The gumboxes are raised or lowered relative to the latex transfer roller manually for cleaning by rotating a hand crank which drives a pinion whose shaft is connected to the gumbox in such a manner that rotation of the pinion is translated into motion which would raise and lower the gumboxes. However, if there is slippage between the hand crank and pinion or the operator's hand is wet so that it slips on the crank, the gumbox can fall or reverse movement spilling its contents and possibly causing injury to the operator.
Accordingly, this invention relates to a friction brake and safety slip clutch device adapted to be positioned between the driven pinion shaft and gumboxes to substantially preclude movement of the gumboxes once rotation of the hand crank driving the pinion has ceased and to further preclude the weight of the gumboxes and sealant material disposed therein from lowering the gumboxes out of position with the gum transfer rollers once a proper elevation for the gumboxes has been attained.